1. Field of the Invention
The present invention relates generally to stand-off assemblies secured to a support member for securing another member thereto. The present invention is particularly adapted for use as a stand-off assembly to attach an umbilical line to a choke or kill line in a marine riser assembly.
2. Description of the Related Art
The need often arises for one elongate member to be secured longitudinally to an elongate support member. This situation often occurs where an umbilical line is required to be secured to a support member or pipe at a certain distance away from the support member. The umbilical line may be a cable, hose or pipe which is run along the length of the support member or pipe.
In the offshore drilling and production industry, it is frequently necessary to run umbilical lines hundreds and even thousands of feet below the support vessel or drilling or production platform down to the sea floor and beyond. Typically, umbilical lines (commonly called control lines) are hydraulic, electric, or fiber optic and they are often separate lines. When the umbilical lines are bundled together in any combination into a single line they are referred to as multiplex control lines or multiplex control cables. These control lines are normally clamped to both the choke line and the kill line on the subsea marine drill riser assembly. Also the control lines are often sent subsea by clamping onto wire lines, drill pipes, casing, and any other available support members. Due to the high cost of working in such environments and serious concerns over loss of functions in a control line, it is critical that the umbilical line be securely attached to the support member to prevent costly consequences, such as loss of signal in a fiber optic cable due to slack in an umbilical line which can create a sharp radius in the line preventing signal transmission. Various types of clamp assemblies and stand-off assemblies have been used in these situations. The prior art clamp assemblies and stand-off assemblies have been very costly and time consuming to make, use and install, and many do not clamp the umbilical lines with enough force.
Applicant's co-pending patent application Ser. No. 08/814,434 entitled "ULTRA HIGH STRENGTH CLAMP ASSEMBLY" discloses an ultra high strength clamp assembly having a flexible strap with first and second ends. The flexible strap extends substantially around the umbilical line and support member and is secured around the umbilical line and support member. The first and second ends are adapted to be coupled to each other or to the support member or to be wrapped twice around the two members resulting in no buckle or attachment being required. The ultra high strength clamp assembly also includes a tensioner assembly having first and second tensioner bars spaced parallel to one another. Each of the first and second tensioner bars includes a bullnose face and the bullnose faces are in opposing relationship to one another. The tensioner assembly also includes an adjusting member for adjusting the spacing between the first and second tensioner bars. The flexible strap extends twice through the space between the first and second tensioner bars, which encloses around the umbilical line. In use, the first and second tensioner bars are situated substantially between the umbilical line and the support member. Applicant herein incorporates by reference U.S. patent application Ser. No. 08/814,434.
As stated above, it is often required that the umbilical line be maintained a certain distance away from the support member. A stand-off assembly is then used to maintain the required distance between the support member and the umbilical line. It is important the stand-off assembly be securely fastened to the support member and also that the umbilical line can be securely attached to the stand-off assembly. In the past, various types of welded stand-off assemblies have been connected to the support member, usually by bolting the stand-off assembly to the support member.
Weight considerations are very important in the design of subsea marine riser assemblies. The greater the weight of the marine riser assembly the more compensation required. Typically, the marine riser assembly includes flotation foam to compensate for the submerged weight of the riser assembly. In very deep water applications, it costs approximately $5.00 for the amount of flotation foam necessary to compensate for each additional pound added to the riser assembly.
It is desirable to have a stand-off assembly that is easy to install, lightweight, has high strength, and is economical to fabricate and install. It is also desirable that the stand-off assembly be adapted for use with applicant's ultra high strength clamp assembly as disclosed in patent application Ser. No. 08/814,434.